The present invention relates to an electric motor including a stator that has three-phase coils wound thereon, and also to a motor-driven compressor using the electric motor.
There is known a motor-driven compressor for use in a vehicle air conditioner, in which an electric motor driven by three-phase ac (alternating current) power to drive the compression mechanism is received in the compressor housing. The electric motor includes a stator having three-phase coils wound thereon, a rotor having permanent magnets, and a rotary shaft rotating with the rotor. Each of the three-phase coils wound on the stator has a pair of end wires. Of the six end wires, three end wires of different phases are tied together as neutral point and fastened to the periphery of the stator, and the other three end wires are used as lead wires. The lead wires are drawn out of the stator after the forming of the coil end. In drawing the lead wires, however, part of the lead wire may enter the space for the rotor. Such lead wire may interfere with the rotor when the rotor and the stator are assembled together, thereby resulting in lead wire breaking.
Japanese Unexamined Patent Application Publication No. 2010-59809 discloses a motor-driven compressor in which a three-phase synchronous electric motor received in the housing is driven by three-phase ac power supplied from the inverter thereby to drive the compression mechanism. The electric motor includes a rotary shaft connected to the compression mechanism, a rotor fixed on the rotary shaft, and a stator fixed in the housing. An inverter housing is mounted to the end wall of the housing to form therein an inverter space where the inverter is provided. The lead wires drawn out from the respective three-phase coils on the stator are connected through a motor harness to a hermetic terminal that is in turn connected to the inverter. The above-cited publication No. 2010-59809 also discloses a structure in which the lead wires are connected to a cluster block that is previously mounted on the periphery of the stator in the housing so as to facilitate the connection between the lead wires and the hermetic terminal.
In the electric motor disclosed in the publication No. 2010-59809, part of the lead wires drawn out from the respective three-phase coils may enter the rotor space. Such lead wire may interfere with the rotor when the rotor and the stator are assembled, which may cause the enamel coating of the lead wire to be scratched and hence lower the insulation performance of the lead wire, thereby resulting in lead wire breaking.
Particularly in the above-described structure in which the cluster block is mounted on the periphery of the stator, the lead wires of the respective coils need to be bent for connection to the cluster block. Such bending of lead wire is required not only in the case that the lead wire is connected to the cluster block after the cluster block is mounted on the periphery of the stator, but also in the case that the cluster block previously connected to the lead wire is mounted on the periphery of the stator.
Part of the lead wire thus bent adjacent to the coil may enter the space for the rotor, and also may interfere with the rotor when the rotor and the stator are assembled, thereby resulting in lead wire breaking. Such problem may occur particularly in the lead wire of the coil whose coil end is located closest to the rotor among the three-phase coils.
The present invention is directed to preventing the lead wire of the coil wound on the stator of an electric motor from entering the space for the rotor of the electric motor.